import React, {Component} from "react";
import {
    ActivityIndicator,
    FlatList,
    RefreshControl,
    StyleSheet,
    Text,
    TouchableNativeFeedback, TouchableOpacity,
    View
} from "react-native";
import { Actions } from 'react-native-router-flux';
const REQUEST_URL = 'http://gank.io/api/data/Android/10/';
let totalPage=5;//总的页数
let itemNo=0;//item的个数
export default class LoadMoreDemo extends Component {
    constructor(props) {
        super(props);
        this.state = {
            page:1,
            isLoading: true,
            //网络请求状态
            error: false,
            errorInfo: "",
            dataArray: [],
            showFoot:0, // 控制foot， 0：隐藏footer  1：已加载完成,没有更多数据   2 ：显示加载中
            isRefreshing:false,//下拉控制
        }
    }
    //网络请求——获取数据
    fetchData() {
        //这个是js的访问网络的方法
        console.log(REQUEST_URL+this.state.page)
        fetch(REQUEST_URL+this.state.page,{
            method: 'GET',
        })
            .then((response) => response.json())
            .then((responseData) => {
                let data = responseData.results;//获取json 数据并存在data数组中
                let dataBlob = [];//这是创建该数组，目的放存在key值的数据，就不会报黄灯了
                let i = itemNo;
                data.map(function (item) {
                    dataBlob.push({
                        key: i,
                        desc: item.desc,
                        time: item.createdAt,
                        who:item.who
                        , url:item.url
                    })
                    i++;
                });
                itemNo = i;
                let foot = 0;
                if(this.state.page>=totalPage){
                    foot = 1;//listView底部显示没有更多数据了
                }
                this.setState({
                    //复制数据源
                  //  dataArray:this.state.dataArray.concat( responseData.results),
                    dataArray:this.state.dataArray.concat( dataBlob),
                    isLoading: false,
                    showFoot:foot,
                    isRefreshing:false,
                });
                data = null;//重置为空
                dataBlob = null;
            })
            .catch((error) => {
                this.setState({
                    error: true,
                    errorInfo: error
                })
            })
            .done();
    }

    componentDidMount() {
        //请求数据
        this.fetchData(  );
    }
    shouldComponentUpdate() {
        return true
    }
    handleRefresh = () => {
        this.setState({
            page:1,
            isRefreshing:true,//tag,下拉刷新中，加载完全，就设置成flase
            dataArray:[]
        });
        this.fetchData()
    }
    itemClick = () => {

        alert("ff")
        {Actions.news}

    }
    //加载等待页
    renderLoadingView() {
        return (
            <View style={styles.container}>
                <ActivityIndicator
                    animating={true}
                    color='blue'
                    size="large"
                />
            </View>
        );
    }
    _keyExtractor = (item, index) => index;
    //加载失败view
    renderErrorView() {
        return (
            <View style={styles.container}>
                <Text>
                    {this.state.errorInfo}
                </Text>
            </View>
        );
    }

    //返回itemView
    _renderItemView({item}) {
        //onPress={gotoDetails()}
        const  gotoDetails=()=>Actions.news({'url':item.url})//跳转并传值
        return (
           // <TouchableNativeFeedback onPress={() => {Actions.news({'url':item.url})}} >////切记不能带（）不能写成gotoDetails()
            <TouchableNativeFeedback onPress={gotoDetails}>
            <View >
                <Text style={styles.title}>{item.desc}</Text>
                <Text style={styles.content}>时间: {item.time}</Text>
                <Text style={styles.content}>作者: {item.who}</Text>
            </View>
            </TouchableNativeFeedback >
        );
    }

    renderData() {
        return (
            <FlatList
                data={this.state.dataArray}
                renderItem={this._renderItemView}
                ListFooterComponent={this._renderFooter.bind(this)}
                onEndReached={this._onEndReached.bind(this)}
                onEndReachedThreshold={1}
                ItemSeparatorComponent={this._separator}
                keyExtractor={this._keyExtractor}
                //为刷新设置颜色
                refreshControl={
                    <RefreshControl
                        refreshing={this.state.isRefreshing}
                        onRefresh={this.handleRefresh.bind(this)}//因为涉及到this.state
                        colors={['#ff0000', '#00ff00','#0000ff','#3ad564']}
                        progressBackgroundColor="#ffffff"
                    />
                }
            />

        );
    }

    render() {
        //第一次加载等待的view
        if (this.state.isLoading && !this.state.error) {
            return this.renderLoadingView();
        } else if (this.state.error) {
            //请求失败view
            return this.renderErrorView();
        }
        //加载数据
        return this.renderData();
    }
    _separator(){
        return <View style={{height:1,backgroundColor:'#999999'}}/>;
    }
    _renderFooter(){
        if (this.state.showFoot === 1) {
            return (
                <View style={{height:30,alignItems:'center',justifyContent:'flex-start',}}>
                    <Text style={{color:'#999999',fontSize:14,marginTop:5,marginBottom:5,}}>
                        没有更多数据了
                    </Text>
                </View>
            );
        } else if(this.state.showFoot === 2) {
            return (
                <View style={styles.footer}>
                    <ActivityIndicator />
                    <Text>正在加载更多数据...</Text>
                </View>
            );
        } else if(this.state.showFoot === 0){
            return (
                <View style={styles.footer}>
                    <Text></Text>
                </View>
            );
        }
    }

    _onEndReached(){
        //如果是正在加载中或没有更多数据了，则返回
        if(this.state.showFoot != 0 ){
            return ;
        }
        //如果当前页大于或等于总页数，那就是到最后一页了，返回
        if((this.state.page!=1) && (this.state.page>=totalPage)){
            return;
        } else {
            this.state.page++;
        }
        //底部显示正在加载更多数据
        this.setState({showFoot:2});
        //获取数据，在componentDidMount()已经请求过数据了
    if (this.state.page>1)
        {
            this.fetchData();
        }
    }
}

const styles = StyleSheet.create({
    container: {
        padding:10,
        flex: 1,
        flexDirection: 'row',
        justifyContent: 'center',
        alignItems: 'center',
        backgroundColor: '#F5FCFF',
    },
    title: {
        marginTop:8,
        marginLeft:8,
        marginRight:8,
        fontSize: 15,
        color: '#ffa700',
    },
    footer:{
        flexDirection:'row',
        height:24,
        justifyContent:'center',
        alignItems:'center',
        marginBottom:10,
    },
    content: {
        marginBottom:8,
        marginLeft:8,
        marginRight:8,
        fontSize: 14,
        color: 'black',
    }
});
